Rare Case of Endoscopically Diagnosed Ischemic Colitis Secondary to Chronic Phentermine Use

Phentermine is an amine anorectic that acts as a sympathomimetic agent and undergoes hepatic metabolism predominantly through CYP3A4. It is commonly used as a mediation to facilitate weight loss. Side effects of phentermine can include pulmonary hypertension, valvular heart disease, palpitations, increased heart rate or blood pressure, diarrhea, and cognitive impairment. Very rarely, phentermine usage has been associated with causing ischemic colitis. The mechanism of action for ischemic colitis from phentermine is not well defined but will be discussed in this review. We present a case of a woman who used phentermine daily for weight loss and was endoscopically confirmed to have ischemic colitis after presenting with abdominal pain and bloody diarrhea.